The Modified Ashworth scale and manual muscle test are important tools for assessing spasticity and strength. Both lack accuracy and reliability, but given their simplicity, will remain widely used. Their reliability and accuracy could be improved if evaluators could practice against a 'bench mark' standard providing accurate and consistent predefined resistive torque profiles. The long term goal of this project is to develop an evaluator training manikin for spasticity and strength assessment practice. The purpose of this project is to develop and test a manikin knee joint for training clinicians to uniformly assess knee spasticity and strength. Aim 1. Develop and test an artificial knee joint that can produce resistive torques over a range of motion. Task 1."Build the Spasticity Strength Knee Assessment Tool (SSKAT). An artificial leg and thigh will be linked by a 1 rotational degree of freedom hinge ('knee') joint. The 'knee' joint will be able to provide a variety of computer controlled resistive torques over 120 degrees of rotation using magneto-rheological fluids. Task 2: Test the SSKAT. The accuracy and reliability of the SSKAT for producing resistive torques will be evaluated by attaching it to a KinCom dynamometer and performing a series of validation tests. Aim 2. Program the SSKAT to mimic the modified Ashworth scale and manual muscle test levels. Task 1. Define and program resistive torque profiles. The 6 resistive profiles defined by the Modified Ashworth Scale and grades 3+ through 5 (5 grades) of the manual muscle tests will be determined for the knee. Computer software will be written to describe these 'bench mark' profiles and control resistive characteristics of the SSKAT. Task 2." Test the SSKAZ. The accuracy and reliability of the SSKAT will be assessed as in Aim 1. Clinicians experienced in using the Ashworth and manual muscle tests will evaluate the ability of the SSKAT to replicate resistive profiles. In addition, the data from the SSKAT will be used to examine clinician reliability. In Phase II, we will develop and test similar devices for the ankle, elbow, hip, and wrist, integrate the components into a training manikin, and consider different torque profiles for men, women, and children.